A pilot for an American Airlines subsidiary was arrested Saturday in the 2015 shooting deaths of three people in Kentucky, the state attorney general announced.

Christian R. Martin, 51, was arrested Saturday at the Louisville airport, a day after he was indicted by a Christian County grand jury in the November 2015 deaths of Calvin and Pamela Phillips of Pembroke and their neighbor, Edward Dansereau, Attorney General Andy Beshear said.

Martin moved from Christian County after the slayings and was living in North Carolina at the time of the indictment, the statement said.

American Airlines said in a statement it is cooperating in the investigation. The airline said Martin has been a pilot for subsidiary PSA Airlines since January 2018. Martin's jail mugshot shows him wearing a pilot's uniform.

A criminal background check conducted on Martin found no "criminal history that would disqualify him from being a commercial pilot," the airline said.

It wasn't immediately known whether Martin has an attorney who could comment on the charges. Martin was being held without bond in the Christian County Detention Center on murder, arson and burglary charges along with tampering with physical evidence.

Police said Calvin Phillips, 59, was found shot to death in the cellar of his home. The bodies of Pamela Phillips, 58, and Dansereau, 63, were found a few miles away in a cornfield inside her burned car.

Authorities have not given a motive for the slayings or said what led them to believe Martin was responsible.

Beshear said he met nearly two years ago with the couple's son, Matt Phillips, who was worried the case had stalled. Beshear accepted a request from the local commonwealth attorney to appoint a special prosecutor to handle the case.

Relatives of Calvin and Pamela Phillips had offered a $100,000 reward to help solve the case.

"I hope this is a day that brings some justice to these families," Beshear said. "There are many steps from here, but we hope this is one example of when you never stop seeking justice, when you never give up, that we can truly get important results for these families."

The statement said relatives of the victims expressed an "overflowing of emotion, sincere relief, and absolute gratitude to all those who have worked diligently on this case."

Passengers who made the trek to the Louisville airport to board their flight told Fox affiliate WDRB that the scene resembled one from a movie.

"It was very tense," Frances Wise, a passenger, told the station. "You could tell the employees knew something was going on."

Wise's daughter, Ashley Martin (no relation to the suspect), called it "startling."

"It's scary to think this happened so long ago, and they're just now getting around to catching the guy," she told the station. "I was definitely stressed. The workers ... you could tell they were stressed. You could feel that energy. You could feel the tension from flight attendants."

After the indictment, American Airlines said Martin has been placed on administrative suspension pending the outcome of the case.

"We have an unwavering commitment to the safety and security of our customers and team members, and we will provide any investigative assistance possible to law enforcement throughout their investigation," according to the Fort Worth-carrier's statement.

Authorities have not released a motive, but the radio station WKDZ-FM reported last year that Calvin Phillips was a potential witness in a previous case against Martin.

The Associated Press and The Washington Post via Bloomberg contributed to this story.